1. Technical Field of the Invention
The present invention relates to a color filter substrate and a method for making the same, an electro-optical device and a method for making the same, and an electronic apparatus. The present invention relates particularly to a structure which can be suitably applied to a light shielding element of a display device.
2. Description of the Related Art
Generally, various electro-optical devices, such as liquid crystal displays, electroluminescent displays, and plasma displays, sometimes comprise color filters in which a plurality of colored layers in different colors are arrayed to achieve color display. In color filters, colored layers of, for example, three colors, i.e., red, green, and blue, are arrayed in a predetermined two-dimensional array pattern such as a stripe array, a diagonal mosaic array, or the like known in the art.
FIG. 10 is a schematic cross-sectional view illustrating the structure of a conventional transflective liquid crystal display 100. The liquid crystal display 100 comprises: a reflecting substrate 110 of a half-transmissive structure including a first substrate 111; a counter substrate 120 including a substrate 121; a liquid crystal layer 130 held between the reflecting substrate 110 and the counter substrate 120; a polarizer 141 and a quarter-wave plate 142 disposed on the outer face of the counter substrate 120; a polarizer 143 and a quarter-wave plate 144 disposed on the outer face of the reflecting substrate 110; and a backlight 150 disposed on the outer face of the polarizer 143.
The reflecting substrate 110 comprises: a reflecting layer 112 formed on the first substrate 111; a transparent insulating layer 113 formed on the reflecting layer 112; electrodes 114 composed of a transparent conductor such as indium tin oxide (ITO); and an alignment film 115.
The counter substrate 120 comprises: light shielding layers 122 formed on the substrate 121; a red colored layer 123R, a green colored layer 123G, and a blue colored layer 123B arranged in pixel regions Pr, Pg, and Pb, respectively, according to a predetermined pattern; a transparent protection layer 124 formed on the colored layers 123R, 123G, and 123B; counter electrodes 125 made of a transparent conductor disposed on the protection layer 124; and an alignment film 126 formed on the counter electrodes 125.
The reflecting layer 112 of the liquid crystal display 100 has an aperture 112a formed in each of the pixel regions Pr, Pg, and Pb and allows light from the backlight 150 to pass through the apertures 112a so as to achieve transmissive display. Meanwhile, since external light entering from the observer side, i.e., the upper side in the drawing, is reflected at the portions of the reflecting layer 112 inside the pixel regions Pr, Pg, and Pb, reflective display is achieved. Thus, the liquid crystal display 100 is of a transflective type.
The light shielding layers 122 are formed on the substrate 121 in positions above the gaps between the pixel regions Pr and Pg, Pg and Pb, and Pb and Pr. Each of the light shielding layers 122 has a laminated structure of two or three layers in which, for example, a chromium thin film and a chromium oxide thin film are stacked so that the light shielding layers 122 hardly reflects external light and appear black when viewed from the observer side, i.e., the upper side in the drawing.
However, in the conventional liquid crystal display 100, the light shielding layers 122 must have a laminated structure to prevent a decrease in the contrast due to reflection at the light shielding layers 122 when viewed from the observer side. Thus, the number of process steps increases, and so does the manufacturing cost, which is a problem.
Moreover, in the light shielding layers 122, the thickness of a reflecting material, such as Cr, must be large enough to achieve a high light-shielding effect; thus, forming the light shielding layers 122 takes long time. This results in a decrease in production efficiency and an increase in manufacturing cost, which is a problem.
Furthermore, although the light shielding layers 122 appear black when observed from the observer side, i.e., from the substrate 121 side, the light shielding layers 122 are configured to reflect light when viewed from the opposite side, i.e., the first substrate 111 side. Thus, in order to avoid a decrease in contrast due to reflection of light at the light shielding layers 122, a color filter comprising colored layers and a protection layer cannot be formed on the reflecting substrate 110, i.e., the substrate at the side opposite to the observer side. Such a structure, which is opposite to the above-described structure, cannot be employed, which is a problem.
The present invention aims to overcome the above-described problems. An object of the present invention is to provide a color filter substrate, an electro-optical device, and methods for manufacturing the same that can prevent an increase in the number of the process steps and the manufacturing cost. Another object of the present invention is to provide a color filter substrate, an electro-optical device, and methods for manufacturing the same that can shorten the time required for forming the light shielding structure and increase the production efficiency. Yet another object of the present invention is to provide a color filter substrate, an electro-optical device, and methods for manufacturing the same that can operate without trouble even when a color filter is formed on the reflecting substrate, i.e., the substrate at the side opposite to the observer side, or when a substrate incorporating a color filter is used as the reflecting substrate, i.e., the substrate at the side opposite to the observer side.
To overcome the above-described problems, the present invention provides a color filter substrate comprising a substrate, a reflective light-shielding layer, and a plurality of colored layers of different colors, wherein the plurality of colored layers of different colors are stacked in a plan view at the reflective light-shielding layer.
According to this invention, a plurality of colored layers of different colors is stacked in a plan view at a reflective light-shielding layer. Thus, particularly when observed from the plurality of colored-layers side, degradation in display contrast due to the reflection of light can be prevented because light reflected at the reflective light-shielding layer can be efficiently absorbed by the plurality of colored layers of different colors. Even when observed from the reflective-light-shielding-layer side, degradation in contrast can also be prevented because the reflectance of the reflective light shielding layer is decreased. In such a case, a sufficient light-shielding effect can be obtained due to the presence of the plurality of colored layers even when the reflectance of the reflective light-shielding layer is decreased.
Since only stacking of the plurality of colored layers at the reflective light-shielding layer is necessary, no additional step is required, thereby preventing an increase in the manufacturing cost. Moreover, since the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer, a sufficient light-shielding effect can be achieved without increasing the thickness of the reflective light-shielding layer, thereby reducing time required to form the reflective light-shielding layer, improving the productivity, and decreasing the cost. Furthermore, a decrease in contrast due to reflection of light can be prevented even when a color filter is formed on a reflecting substrate or a substrate at the side opposite to the observation side.
The reflective light-shielding layer is preferably composed of metal material to reduce the manufacturing cost and time. The metal material may be aluminum, silver, tantalum, nickel, chromium, or an alloy thereof.
In preparing a primary-color system color filter, for example, red (R), green (g), and blue (b) colored layers are used as the above-described colored layers. In this case, at least two colored layers of two different colors among three colors must be stacked in a plan view at the reflective light-shielding layer. In this invention, preferably, the colored layers of all the colors, i.e., three colored layers in the above example, are stacked in a plan view at the reflective light-shielding layer so as to reduce reflected light at the reflective light-shielding layer.
In this invention, preferably, the reflective light-shielding layer is disposed on the substrate, and the plurality of colored layers of different colors are stacked on the reflective light-shielding layer.
According to this invention, reflection of light at the reflective light-shielding layer can be decreased and a decrease in display contrast can be prevented particularly when the substrate of an electro-optical device is disposed at the side opposite to the observation side.
In this invention, a reflecting layer is preferably formed inside a region where only one of the plurality of colored layers is provided. More preferably, the reflective light-shielding layer is either integral with the reflecting layer or composed of the same material as that of the reflecting layer.
According to this invention, because the reflective light-shielding layer is integral with the reflecting layer or is made of the same material as the reflecting layer, the reflective light-shielding layer and the reflecting layer can be formed in the same step. Thus, the number of steps can be decreased, and so can the manufacturing cost.
In this invention, the colored layers stacked in a plan view at the reflective light-shielding layer preferably include a red colored layer and a blue colored layer.
According to this invention, since the red colored layer and the blue colored layer are stacked in a plan view at the reflective light-shielding layer, almost all light in the visible wavelength region reflected at the reflective light-shielding layer can be sufficiently absorbed by the colored layers. Thus, a decrease in display contrast due to the reflection of light can be prevented.
In this invention, only a colored layer of one color out of the plurality of colored layers is preferably formed in a region disposed on one side of the reflective light-shielding layer, and only another colored layer of a different color out of the plurality of colored layers is formed in a region disposed on the other side of the reflective light-shielding layer. The colored layers of the one color and the different color preferably extend over the reflective light-shielding layer so as to be stacked.
According to this invention, because the colored layers in the regions adjacent to the reflective light-shielding layer, i.e., the regions being disposed respectively at one side and the other side of the reflective light-shielding layer, extend over the reflective light-shielding layer, the array pattern of the colored layers can be simplified, thereby facilitating the production. Herein, the term xe2x80x9cthe other sidexe2x80x9d does not necessarily mean the side opposite to the xe2x80x9cone sidexe2x80x9d but means simply a different side from the xe2x80x9cone sidexe2x80x9d.
Next, the present invention provides a method for making a color filter substrate comprising a substrate, a reflective light-shielding layer, and a plurality of colored layers of different colors, the method comprising a step of forming the plurality of colored layers of different colors so that the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer.
According to this invention, the plurality of colored layers of different colors is stacked in a plan view at the reflective light-shielding layer. Thus, when observed from the colored-layers side, degradation in display contrast due to the reflection of light can be prevented because light reflected at the reflective light-shielding layer can be efficiently absorbed by the colored layers of different colors. Even when observed from the reflective-light-shielding-layer side, degradation in contrast can also be prevented because the reflectance of the reflective light shielding layer is decreased. In such a case, a sufficient light-shielding effect can be obtained due to the presence of the plural colored layers even when the reflectance of the reflective light-shielding layer is decreased.
Since only stacking of the plural colored layers at the reflective light-shielding layer in a plan view is necessary, no additional step is required, thereby preventing an increase in the manufacturing cost. Moreover, since the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer, a sufficient light-shielding effect can be achieved without increasing the thickness of the reflective light-shielding layer, thereby reducing time required for forming the reflective light-shielding layer, improving the productivity, and decreasing the cost. Furthermore, a decrease in contrast due to reflection of light can be prevented even when a color filter is formed on a reflecting substrate or a substrate at the side opposite to the observation side.
In this invention, the reflective light-shielding layer is preferably formed on the substrate, and the plurality of colored layers of different colors are preferably stacked on the reflective light-shielding layer.
According to this invention, the reflection of light at the reflective light-shielding layer can be decreased and a decrease in display contrast can be prevented when the color filter substrate of an electro-optical device is disposed at the side opposite to the observation side.
In this invention, a reflecting layer is preferably formed in a region where only one of the plurality of colored layers is formed, and, preferably, the reflective light-shielding layer and the reflecting layer are simultaneously formed with the same material.
According to this invention, because the reflective light-shielding layer and the reflecting layer can be simultaneously formed with the same material, the number of steps can be decreased, and so can the manufacturing cost.
In this invention, the colored layers stacked in a plan view at the reflective light-shielding layer preferably include a red colored layer and a blue colored layer.
According to this invention, since the red colored layer and the blue colored layer are stacked in a plan view at the reflective light-shielding layer, almost all light in the visible wavelength region reflected at the reflective light-shielding layer can be sufficiently absorbed by the colored layers. Thus, a decrease in display contrast due to the reflection of light can be prevented.
In this invention, preferably, only a colored layer of one color out of the plurality of colored layers is formed in a region on one side of the reflective light-shielding layer, only another colored layer of a different color out of the plurality of colored layers is formed in a region on another side of the reflective light-shielding layer, and the colored layers of the one color and the different color extend over the reflective light-shielding layer so as to be stacked thereat.
According to this invention, because the colored layers in the regions adjacent to the reflective light-shielding layer, i.e., the regions being disposed at both sides of the reflective light-shielding layer, extend over the reflective light-shielding layer, the array pattern of the colored layers can be simplified, thereby facilitating the production.
Next, the present invention provides an electro-optical device comprising an electro-optical layer, a reflective light-shielding layer, and a plurality of colored layers of different colors. The plurality of colored layers of different colors are stacked at the reflective light-shielding layer.
According to this invention, the plurality of colored layers of different colors is stacked in a plan view at the reflective light-shielding layer. Thus, when observed from the plurality of colored-layers side, degradation in display contrast due to the reflection of light can be prevented because light reflected at the reflective light-shielding layer can be efficiently absorbed by the plurality of colored layers of different colors. Even when observed from the reflective-light-shielding-layer side, degradation in contrast can also be prevented because the reflectance of the reflective light shielding layer is decreased. In such a case, a sufficient light-shielding effect can be obtained due to the presence of the plurality of colored layers even when the reflectance of the reflective light-shielding layer is decreased.
Since only stacking of the plural colored layers at the reflective light-shielding layer in a plan view is necessary, no additional step is required, thereby preventing an increase in the manufacturing cost. Moreover, since the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer, a sufficient light-shielding effect can be achieved without increasing the thickness of the reflective light-shielding layer, thereby shortening the time required for forming the reflective light-shielding layer, improving the productivity, and decreasing the cost. Furthermore, a decrease in contrast due to reflection of light can be prevented even when a color filter is formed on a reflecting substrate or a substrate at the side opposite to the observation side.
The reflective light-shielding layer is preferably composed of metal to reduce the manufacturing cost and time. The metal material may be aluminum, silver, tantalum, nickel, chromium, or an alloy thereof.
In preparing a primary-color system color filter, for example, red (R), green (G), and blue (B) colored layers are used as the above-described colored layers. In this case, at least two colored layers of two different colors among three colors must be stacked in a plan view at the reflective light-shielding layer. In this invention, preferably, the colored layers of all the colors, i.e., three colored layers in the above example, are stacked in a plan view at the reflective light-shielding layer so as to reduce reflected light at the reflective light-shielding layer.
It should be noted that in this invention, as described below, the reflective light-shielding layer is preferably disposed at the side opposite to the observation side of the device relative to the plurality of colored layers stacked in a plan view. However, even when the reflective light-shielding layer is disposed at the observation side of the device relative to the plurality of colored layers stacked in a plan view, light can still be sufficiently shielded because the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer. A sufficient light-shielding effect can be achieved when the thickness of reflective light-shielding layer is reduced to decrease the reflectance of the reflective light-shielding layer. Thus, degradation in display contrast due to the reflection of light at the reflective light-shielding layer can be prevented.
In this invention, the reflective light-shielding layer is preferably disposed on a substrate, and the plurality of colored layers of different colors are preferably stacked in a plan view on the reflective light-shielding layer.
According to this invention, when viewed from the colored-layers side, the reflection of light at the reflective light-shielding layer can be decreased, and a decrease in display contrast can be prevented. Thus, even when the substrate is disposed in the electro-optical device at the side opposite to the observation side, reflection of light can be prevented, and light can be satisfactorily shielded.
In this invention, a reflecting layer is preferably disposed in the region where only one of the plurality of colored layers is formed. In this case, the reflective light-shielding layer is preferably either integral with the reflecting layer, or composed of the same material as that of the reflecting layer.
According to this invention, because the reflective light-shielding layer is integral with the reflecting layer or is made of the same material as the reflecting layer, the reflective light-shielding layer and the reflecting layer can be formed in the same step. Thus, the number of steps can be decreased, and so can the manufacturing cost.
In this invention, the colored layers stacked in a plan view at the reflective light-shielding layer preferably include a red colored layer and a blue colored layer.
According to this invention, since the red colored layer and the blue colored layer are stacked in a plan view at the reflective light-shielding layer, almost all light in the visible wavelength region reflected at the reflective light-shielding layer can be sufficiently absorbed by the colored layers. Thus, a decrease in display contrast due to the reflection of light can be prevented.
In this invention, a colored layer of one color is preferably formed in a region disposed on one side of the reflective light-shielding layer, and another colored layer of a different color is preferably formed in a region disposed on another side of the reflective light-shielding layer. The colored layers of the one color and the different color preferably extend over the reflective light-shielding layer so as to be stacked thereat.
According to this invention, because the colored layers in the regions adjacent to the reflective light-shielding layer, i.e., the regions being disposed at both sides of the reflective light-shielding layer, extend over the reflective light-shielding layer, the array pattern of the colored layers can be simplified, thereby facilitating the production.
In this invention, the reflective light-shielding layer is preferably disposed at the side of the stacked colored layers opposite to a viewing side of the device.
According to this invention, because the reflective light-shielding layer is disposed at the side opposite to the observation side of the device relative to the plurality of colored layers stacked in a plan view, reflection of light at the reflective light-shielding layer is hardly recognizable in the display. Thus, a decrease in display contrast can be prevented.
Next, the present invention provides a method for making an electro-optical device comprising an electro-optical layer, a reflective light-shielding layer, and a plurality of colored layers of different colors, the method comprising a step forming the plurality of colored layers of different colors so that the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer.
According to this invention, a plurality of colored layers of different colors is stacked at a reflective light-shielding layer. Thus, when observed from the plurality of colored-layers side, degradation in display contrast due to the reflection of light can be prevented because light reflected at the reflective light-shielding layer can be efficiently absorbed by the colored layers of different colors. Even when observed from the reflective-light-shielding-layer side, degradation in contrast can also be prevented because the reflectance of the reflective light shielding layer is decreased. In such a case, a sufficient light-shielding effect can be obtained due to the presence of the plurality of colored layers even when the reflectance of the reflective light-shielding layer is decreased.
Since only stacking of the plurality of colored layers at the reflective light-shielding layer in a plan view is necessary, no additional step is required, thereby preventing an increase in the manufacturing cost. Moreover, since the plurality of colored layers are stacked in a plan view at the reflective light-shielding layer, a sufficient light-shielding effect can be achieved without increasing the thickness of the reflective light-shielding layer, thereby reducing the time required for forming the reflective light-shielding layer, improving the productivity, and decreasing the cost. Furthermore, a decrease in contrast due to reflection of light can be prevented even when a color filter is formed on a reflecting substrate or a substrate at the side opposite to the observation side.
In this invention, preferably, the reflective light shielding layer is formed on a substrate, and the colored layers of different colors are formed on the reflective light-shielding layer so that the colored layers of different colors are stacked thereon in a plan view.
According to this invention, reflection of light at the reflective light-shielding layer can be decreased and a decrease in display contrast can be prevented when the color filter substrate comprising the substrate disposed at the side opposite to the observation side is employed.
In this invention, preferably, a reflecting layer is formed inside a region where only one of the plurality of colored layers is provided, and the reflecting layer and the reflective light-shielding layer are simultaneously formed with the same material.
According to this invention, because the reflective light-shielding layer and the reflecting layer can be simultaneously formed with the same material, the number of steps can be decreased, and so can the manufacturing cost.
In this invention, preferably, the colored layers stacked in a plan view at the reflective light-shielding layer include a red colored layer and a blue colored layer.
According to this invention, since the red colored layer and the blue colored layer are stacked in a plan view at the reflective light-shielding layer, almost all light in the visible wavelength region reflected at the reflective light-shielding layer can be sufficiently absorbed by the colored layers. Thus, a decrease in display contrast due to the reflection of light can be prevented.
In this invention, preferably, only one color layer of one color out of the plurality of colored layers is formed in a region on one side of the reflective light-shielding layer, and only another colored layer of a different color out of the plurality of colored layers is formed in a region on another side of the reflective light-shielding layer. The colored layers of the one color and the different color preferably extend over the reflective light-shielding layer so as to be stacked thereat.
According to this invention, because the colored layers in the regions adjacent to the reflective light-shielding layer, i.e., the regions being disposed at both sides of the reflective light-shielding layer, extend over the reflective light-shielding layer, the array pattern of the colored layers can be simplified, thereby facilitating the production.
Next, the present invention provides an electronic device including any one of the above-described electro-optical devices and a controlling unit for controlling the electro-optical device. In various electronic apparatuses incorporating the present invention, the display section of the electronic device can be easily observed since reflection of light can be decreased while maintaining a light-shielding effect and a decrease in display contrast can be inhibited. Moreover, an increase in manufacturing cost can be inhibited, and the electronic apparatuses can be supplied at lower prices. The present invention is particularly suitable when applied to portable electronic apparatuses such as cellular phones and portable information terminals.